The present invention relates to a pneumatic tire and, more specifically, to a pneumatic tire capable of compatibly achieving both drainage performance and uneven wear resistance.
In general, it has been known that a straight groove extending on the tread surface of a pneumatic tire in a circumferential direction of the tire can provide a drainage effect during straight running, and a slant groove extending obliquely relative to the tire circumferential direction thereon can provide high drainage during turning. Thus, conventionally, in order to secure high drainage performance during both straight running and turning, a tread pattern combining the straight groove or grooves with the slant grooves has been proposed.
An example is illustrated in FIG. 2. Three straight main grooves 12 are disposed on a tread surface 11 extending in a tire circumferential direction T and drainage is secured during straight running by these three straight main grooves 12. A tire inner portion of each lateral groove 13 obliquely extending in a tire width direction is formed as a slant groove section 13a and drainage is enhanced during turning by the slant groove sections 13a. 
However, when the slant groove sections 13a are disposed as described above, a contact pressure distribution of each block 14 defined by the straight main grooves 12 and the lateral grooves 13 results in non-uniform, causing a reduction in uneven wear resistance. Thus, in terms of the pneumatic tire having a block pattern defined by straight grooves and slant grooves, there has been a difficulty in achieving both drainage performance and uneven wear resistance.